Offshore oil drilling requires the transportation of hydrocarbons from wellheads positioned underwater to shore or other surface equipment for further distribution. As temperature decreases the resistance to flow of liquids such as oil increases. Pipelines used in the transportation of oil from the underwater wellheads are generally insulated to avoid a substantial decrease in the temperature of the oil. Moreover, the underwater environment exposes pipelines and other oil drilling equipment to compressive forces, salt water corrosion, near-freezing water temperatures, possible water absorption, undersea currents, and marine life. Most pipes and pipelines used in offshore oil drilling are constructed of metal, typically some grade of steel.
Installation conditions for subterranean and subsea pipelines and equipment tend to be demanding. As such, it is possible that the material used to thermally insulate offshore drilling equipment and pipelines, including but not limited to subterranean pipelines and equipment as well as subsea pipelines and equipment may become damaged during installation of the pipeline. For example, during installation pipeline insulation undergo bending (flexural stress) due to pipe sag and reeling, particularly in what are commonly known as S-lay and J-lay installation processes.
In recent years performance requirements for thermal insulation materials have also become increasingly demanding. Recent advances in drilling technology and depletion of readily accessible sub-sea oil wells have resulted in the push toward deep water drilling where oil temperatures are typically hotter. This results in higher temperature pipelines and structures. Though several materials (e.g., polymer materials and/or polymer composite materials) with higher design temperatures have been developed, the peak use temperature of these materials has plateaued near 150-160° C. Thus, a need exists for easily applied thermal insulation materials that pass the requisite qualification tests so as to be suitable for use on subsea and subterranean pipelines with maximum flowline operating temperatures (MFOTs) above 150-160° C. These installation and performance demands, as well as other needs, have led to the introduction of a number of materials (e.g., polymer materials and/or polymer composite materials) for the purpose of insulating offshore drilling equipment and pipelines, including but not limited to subterranean pipelines and equipment as well as subsea pipelines and equipment.
Desirable characteristics and/or properties of thermal insulation materials, in particular thermal insulation materials for subsea applications include: thermal stability above 175° C.; resistance to hydrolysis above 175° C.; flexibility greater than 5% elongation at break at 25° C.; compatibility with glass microspheres; fast cure times; low thermal conductivity; high impact strength; castable (high throughput with low capital expenditure cost); rigid for robust pipe handling without external protection; can be processed in air; can be applied in thick sections without multi-layering; can be applied to complex geometries; rapid full cure under production conditions; processable in the presence of trace moisture (water). Furthermore, there has been a need in the industry for thermal insulation materials, particularly thermal insulation materials for subsea applications (e.g., thermal insulation for pipe and pipelines and other subsea equipment and structures, such as coatings for field joints, etc.) that possess all of these desirable characteristics and/or properties. Thermal stability as used herein means that a material maintains its structural integrity when subjected to elevated temperatures.
Polyurethanes have been used for insulating subsea pipelines and equipment due to somewhat general ease in processing and generally good mechanical properties. However, polyurethane insulation may suffer from hydrolytic degradation when exposed to hot-wet environments. In offshore oil fields, particularly fields where the oil temperature is high at the wellhead, there is a possibility of hydrolytic degradation of the polyurethane polymer network, particularly at elevated temperatures where water is able to ingress the polymer network, which would negatively affect the insulation capabilities of the polyurethane polymer.
Polypropylene is another polymer material that is used to insulate subsea pipelines and equipment. However, unlike polyurethanes, the application of polypropylene is a more difficult process generally requiring extrusion of multiple layers. Moreover, polypropylene does not possess attractive thermal and mechanical properties.
Polystyrene is another polymer material that is used to insulate subsea pipelines and equipment, however, polystyrene does not possess attractive thermal and mechanical properties.
Another material used for insulating subsea pipelines and equipment is rigid epoxy syntactic foam, where hollow glass or ceramic spheres are combined with the epoxy resin. This material possesses good thermal conductivity, but suffers from being very brittle and rigid, making this material susceptible to damage when exposed to high stress forces and/or sudden impacts. Moreover, these materials are difficult to remove and replace as they are attached to the surface mechanically or through the use of adhesives. Epoxy resin in general, in the absence of glass or ceramic microspheres, have poor thermal conductivity, generally require long cure cycles and also suffer from being very brittle and rigid, and well as having other limitations.
Silicones and syntactic silicones where hollow glass or ceramic spheres are combined with the silicones are another polymer material that is used to insulate subsea pipelines and equipment, however, silicones and syntactic silicones may suffer from hydrolytic degradation when exposed to hot wet environments. Moreover, silicones generally require long cure cycles.
Phenolics are another polymer material that is used to insulate subsea pipelines and equipment; however, phenolics are generally difficult to apply to such objects. These materials also suffer from being very brittle and rigid, making this material susceptible to damage when exposed to high stress forces and/or sudden impacts.
Another material for insulating subsea pipelines and equipment is elastomeric amine cured epoxy resins. While elastomeric amine cured epoxy resins may offer some advantages over polyurethanes, these materials possess several limitations, particularly in that at least two steps and specialized equipment are required to prepare such elastomeric amine cured epoxy resins. Moreover, these materials are viscous liquids (e.g., 90,000 cP at 25° C.), making the filling of complex molds difficult.
Rubber materials, including silicone rubber, are examples of other materials used to insulate subsea pipelines and equipment. These materials do not possess attractive thermal and mechanical properties, and generally require long cure cycles, as well as having other limitations.
Dicyclopentadiene polymer (pDCPD) prepared from Telene® 1650 DCPD resin is another example of a material that has been reported for use as a field joint coating material, however, this material (including similar materials such as Metton® DCPD resin and Pentam® DCPD resin) possess several limitations, which are well known in the art. Telene® 1650 DCPD resin (BF Goodrich/Telene SAS) and Metton® DCPD resin (Metton America/Hercules) are both based on a two component system comprising molybdenum (Telene SAS/BF Goodrich) or tungsten (Metton America/Hercules) pre-catalyst dissolved in DCPD monomer (B-component) and an aluminum alkyl or aluminum alkyl halide co-catalyst dissolved in DCPD monomer (A-component). These molybdenum and tungsten catalyzed DCPD resins are extremely sensitive to chemical functional groups and to air (oxygen) and moisture (water), even at trace levels. As a result of this sensitivity, such molybdenum and tungsten catalyzed DCPD resin are typically limited to being processed using Reaction Injection Molding (RIM) techniques, which require specialized and expensive processing and handling conditions and equipment, including specialized and expensive molds, injection equipment, and storage tanks. Moreover, as a further result of this sensitivity, particularly their sensitivity to chemical functional groups, such molybdenum and tungsten catalyzed DCPD resins are generally not suitable for use to prepare DCPD polymer composites.
In fact, commercially available DCPD monomer resins for use in molding of polymer articles typically contain between 0%-30% by weight of tricyclopentadiene, and lesser amounts of higher oligomers of cyclopentadiene such as tetramers and pentamers of cyclopentadiene (e.g., tetracyclopentadiene and pentacyclopentadiene).
Therefore, despite the advances achieved in the art, there continues to be need for improvements in the materials, particularly polymer materials and/or polymer composite materials, used for thermally insulating pipelines and associated equipment and structures used in offshore oil drilling.